This application relates to an ink jet cartridge or cassette as used in an ink jet printer, and more particularly to an ink cartridge apparatus and method of assembling same for realizing an improved back pressure characteristic in the ink contained within the cartridge. It will be appreciated, however, that the invention may find application in related environments and applications where back pressure of ink contained within a vessel is important to operation of the device.
It is generally known in the art to form a cartridge housing or body from a plastic material. The housing includes one or more cavities or chambers that hold a predetermined supply of ink. For example, a single color of ink may be provided in a single chamber cartridge or multiple chambers may be provided, for example, each holding a different color ink stored therein for selective use in a color printer. It is also generally known to provide a hydrophilic foam ink absorbing member such as a reticulated polyethylene, polyurethane, or melamine foam that fits within the chamber(s). In some arrangements, the ink absorbing member fills the substantial entirety of the chamber, while in other instances, a portion of the ink supply is free ink and the remainder is stored in the ink absorbing member. One or more outlet ports are located in close proximity to the ink absorbing member(s) and communicate with the respective one or more chambers through outlet passages. The outlet passage proceeds through a first or bottom wall of the housing. A supply needle from an associated printer extends through the outlet port and thus conveys ink from the housing to a recording head or print head.
Print quality can be adversely affected by an improper amount of back pressure in the ink contained within the cartridge, particularly in the area adjacent the outlet port and supply needle. Thus, manufacturers of ink cartridges are careful in the design, assembly, shipment, and storage of ink cartridges. One way manufacturers have addressed the issue of back pressure of the ink within the cartridge is through the selection of foam materials having the desired characteristics. Pore size is an important design consideration. Additionally, materials selected from the group including melamine and polyethylene have demonstrated some ability to produce modest back pressure in the ink contained within the cartridge.
Although these attempts have met with success more or less, there is a need in the art for an ink cartridge having an improved foam element therein which provides the desired back pressure characteristic in the ink contained within the cartridge so that print quality is improved.